Pannus in Dogs: Chronic Superficial Keratitis Explained

If you have noticed a pink, fleshy film creeping across the clear surface of your dog's eye, or a brown or black haze spreading slowly from the edge toward the center, your veterinarian may mention a condition called pannus. Its formal name is chronic superficial keratitis, which simply means long-lasting inflammation of the outer layers of the cornea. Pannus is usually not painful in its early stages, so many dogs act completely normal while the changes build. Left unmanaged, though, the tissue and pigment can cover enough of the cornea to blur or block vision. Most dogs do well with consistent care. This guide explains what pannus is, which dogs are most often affected, why sunlight matters, how veterinarians diagnose it, what lifelong management looks like, and which eye signs mean you should contact your veterinarian right away.

Important: This article shares general educational information for pet owners and is not a substitute for an in-person veterinary examination, diagnosis, or treatment. For any medical concern or emergency, contact your veterinarian promptly.

What Is Pannus?

The cornea is the clear, dome-shaped window at the front of the eye. It has no blood vessels of its own and stays transparent so that light can pass through to the back of the eye. In pannus, the immune system mistakenly targets the cornea, and this inflammation causes blood vessels, inflammatory cells, and scar-like tissue to grow into the corneal surface. Over time, pigment cells often follow, leaving dark patches behind.

Pannus is considered an immune-mediated condition. It is not caused by an infection and is not contagious, and environmental factors, especially ultraviolet light, appear to make the immune response stronger.

The condition almost always affects both eyes, although one eye may look worse than the other. It typically begins at the outer edge of the cornea, on the side closest to the ear, and gradually spreads toward the center.

Which Dogs Are Most Often Affected?

Any dog can develop pannus, but it is most commonly reported in German Shepherds and German Shepherd mixes. It is also described in some sighthound breeds, such as Greyhounds, and in related herding breeds like the Belgian Tervuren. A genetic tendency is believed to play a role.

Pannus usually appears in adult dogs rather than puppies. Dogs that develop it earlier in life sometimes have a more progressive course, which is one reason your veterinarian may recommend closer monitoring for younger patients.

If your dog is a breed known to be at risk, check the eyes regularly. Catching pannus early generally makes it easier to control.

Why Sunlight and Altitude Matter

Ultraviolet (UV) light is the best-known aggravating factor for pannus. UV exposure is thought to alter corneal tissue in a way that makes the immune system more likely to react against it. This is why pannus often looks more active in sunny seasons and can be more challenging for dogs at high altitude, where UV levels are stronger.

Other factors that can add to UV exposure

• Time outdoors: dogs that spend long hours outside, especially in the middle of the day, receive more UV light.
• Reflective surfaces: snow, sand, water, and light-colored concrete can bounce extra UV light toward the eyes.
• Altitude: UV intensity increases as elevation rises, so mountain living or hiking trips can matter.
• Seasonal changes: longer, brighter days may bring flare-ups.

Sunlight does not cause pannus on its own, but limiting exposure is an important supportive step. Our guide to sun safety for dogs and cats covers general shade and timing tips.

What Pannus Looks Like

Pannus changes develop slowly, so they are easy to miss at first.

Corneal changes

• Pink or red fleshy tissue: a raised, velvety film that often starts at the outer edge of the cornea.
• Fine blood vessels: thin red lines reaching across the clear surface of the eye.
• Brown or black pigment: darker patches that may follow the pink tissue and can remain even after inflammation settles.
• Cloudy or hazy areas: a grayish or whitish look in parts of the cornea.

Third eyelid changes

Some dogs also develop inflammation of the third eyelid, the thin membrane in the inner corner of the eye. This form is sometimes called plasmoma or atypical pannus. The edge of the third eyelid may look thickened, pink, and lumpy, and it may lose some of its normal dark pigment. It can occur alone or together with corneal changes. If you have noticed this membrane looking more prominent, our article on the third eyelid showing in dogs and cats explains the many possible reasons.

Pannus by itself is usually not painful. Squinting, heavy tearing, or pawing at the eye suggests something else may be going on, and a cloudy eye with squinting needs veterinary attention right away.

How Veterinarians Diagnose Pannus

Pannus is usually diagnosed through a thorough eye exam, often combined with the dog's breed, age, and the typical location of the changes. Your veterinarian may refer you to a veterinary ophthalmologist for complex cases.

1. History: your veterinarian will ask when you first noticed the changes, how much time your dog spends outdoors, and whether anything seems to bother the eyes.
2. Close eye exam: a bright light and magnification allow a detailed look at the cornea, third eyelid, and eyelids.
3. Fluorescein stain: a harmless dye checks for scratches or ulcers on the cornea, which need different care.
4. Tear production test: a small paper strip measures tear output, since dry eye can look similar or occur alongside pannus.
5. Eye pressure check: measuring pressure inside the eye helps rule out other conditions such as glaucoma.
6. Cytology if needed: a gentle sample of surface cells may be examined in unusual cases to support the diagnosis.

These steps help distinguish pannus from other causes of redness, cloudiness, or pigment, such as chronic dry eye or injury.

Lifelong Management: The Goal Is Control

Pannus is lifelong, but in most dogs it can be controlled very well. The goal is long-term control: quieting the immune reaction, keeping the tissue from spreading, and helping preserve vision. Some of the pink tissue and haze may fade with consistent care, although dark pigment often remains.

Prescription eye medication

The foundation of management is topical medication applied directly to the eye. Your veterinarian may prescribe topical corticosteroids, topical immunomodulating medication, or a combination of both, always as prescribed by your veterinarian. Medication is often given more frequently at first, then adjusted to the lowest amount that keeps the eyes quiet. Never use leftover eye medication from a previous problem, because some eye drops are unsafe if the cornea is scratched or ulcerated.

Ongoing rechecks

Regular rechecks let your veterinarian check progress and side effects and adjust the plan through the seasons. Many dogs need more medication during sunny months and less during darker months.

Other options in select cases

In more advanced or difficult cases, your veterinarian or a veterinary ophthalmologist may discuss additional options. These are chosen case by case.

Supportive Care at Home

Home care supports, but never replaces, the medication plan your veterinarian prescribes. Consistency is the most important factor in keeping pannus under control.

Goggles and shade are supportive measures only. They work best alongside prescribed medication, not instead of it.

When to Call Your Veterinarian

Any new pink tissue, pigment, or haze on your dog's eye warrants a veterinary exam. Schedule an appointment soon if you notice:

• A pink or red film spreading across the clear part of the eye
• Brown or black pigment appearing or growing on the cornea
• A thickened, pink, or lumpy edge on the third eyelid
• Changes that return or worsen after medication was lowered
• Difficulty giving drops consistently, so your veterinarian can help adjust the plan
• Gradually declining confidence in dim light

Contact your veterinarian or an emergency clinic right away if

• Your dog shows sudden eye pain, such as holding the eye shut, pawing at it, or rubbing the face
• The eye becomes cloudy and your dog is squinting
• Your dog suddenly seems unable to see
• The eye looks bulging, very red, or has thick discharge
• There has been any injury to the eye

Sudden pain and squinting can signal a corneal ulcer or another urgent problem. Our article on corneal ulcers in dogs and cats explains why these are urgent.

Common Mistakes and Myths

Myth: Pannus is just a cosmetic problem.

Fact: although it often looks only cosmetic at first, untreated pannus can spread far enough to cover much of the cornea and impair vision.

Mistake: Quitting the drops once the eyes look clear.

Pannus is lifelong, and ending medication without guidance commonly leads to a flare-up.

Mistake: Using old or borrowed eye drops.

Some eye medications can be harmful if a dog has a corneal ulcer. Only use products your veterinarian has prescribed for the current problem.

Myth: Goggles alone can manage pannus.

Fact: eyewear and shade limit UV exposure, but they do not calm the immune reaction. They are a helpful addition to prescription medication.

Living Well With a Dog Who Has Pannus

Most dogs with well-managed pannus live full, active lives. Giving eye medication often becomes a quick part of the day. Pairing drops with a favorite snack or a short play session makes the routine pleasant.

Plan outdoor activities with sunlight in mind. Early morning and evening walks, shaded trails, and breaks under cover all help. If you travel to mountains or snowy areas, talk with your veterinarian ahead of time about adjusting the plan.

Frequently Asked Questions

Is pannus painful for dogs?

Pannus itself is usually not painful. If your dog is squinting, pawing at the eye, or holding it shut, contact your veterinarian right away, because these signs suggest another problem such as an ulcer.

Will my dog go blind from pannus?

With consistent management, many dogs keep useful vision for life. Vision loss is more likely when the condition is left unmanaged or medication is discontinued.

Can the dark pigment go away?

Pink tissue and haze often fade with consistent care, but pigment tends to remain. Your veterinarian's goal is to keep it from spreading further.

Is pannus contagious?

No. It is an immune-mediated condition, so it does not spread to other pets or people.

Will my dog need medication forever?

Most dogs need some level of ongoing eye medication. Your veterinarian will aim for the lowest amount that keeps the eyes under control.

Key Takeaways

Pannus, or chronic superficial keratitis, is a lifelong immune-mediated condition in which pink, fleshy tissue and dark pigment spread across the cornea, often starting at the outer edge of both eyes. It is most commonly reported in German Shepherds and some sighthound and herding breeds, and UV light and high altitude make it worse. The third eyelid can also be involved in a form called plasmoma. Diagnosis is made through a careful eye exam. Management aims for long-term control using topical corticosteroids or immunomodulating eye medication as prescribed by your veterinarian, supported by shade, well-fitted dog goggles, and regular rechecks. Contact your veterinarian or an emergency clinic right away for sudden eye pain, a cloudy eye with squinting, or sudden vision loss.